July 2011 Archive for Dairy Today Healthline

Due to variations in breeding programs and how quickly cows become pregnant, select a vaccine that has sufficient duration of immunity to help protect the cow throughout all risk periods prior to and during gestation.

By Greg Edwards, DVM, senior veterinarian, Pfizer Animal Health

Dairy producers focused on improving reproductive performance shouldn’t overlook vaccination programs. A great deal of time, energy and money is invested to ensure reproductive success, and a well-planned vaccination program can help maximize that investment by limiting issues caused by various reproductive diseases.

The most common and troublesome problems producers face throughout a cow’s lactation can include:

Getting the cow off to a good start after calving is the first step toward reproductive success later in lactation. A vaccine that offers protection against both BVD and Lepto-hardjo bovis will help protect against infertility that may prevent a cow from becoming pregnant in a timely manner. Due to variations in breeding programs and how quickly cows become pregnant, select a vaccine that has sufficient duration of immunity (DOI) to help protect the cow throughout all risk periods prior to and during gestation.

After conception, protecting the fetus is an important goal of vaccination programs. A calf in utero relies on the dam’s immune system to prevent pathogens from crossing the placenta. The dam’s antibodies do not cross the placenta and the fetus does not develop its own immune system until sometime in the third trimester. The calf will not have adequate circulating antibodies to protect itself until it absorbs them from colostrum after birth.

Duration of immunity is important

When choosing the right vaccines for your herd, keep the needs of the developing fetus in the forefront. More than 100 reproductive vaccines are approved for use in cattle, but only three offer fetal protection against PI calves, infectious bovine rhinotracheitis (IBR) abortions and Lepto hardjo-bovis, as well as have USDA-approved DOI claims.

DOI is an important factor to help ensure protection through the “critical risk” periods, when the dam and/or fetus are at highest risk from exposure to a pathogen. Protection is needed throughout the critical risk periods, which vary by pathogen, as follows:

BVD - 0 to 281 days

BVD PI - 40 to 120 days

IBR abortion - 0 to 281 days

Lepto hardjo-bovis - 0 to 95 days

Other species of leptospirosis* - 0 to 281 days

*No vaccines have an established DOI other than for hardjo-bovis.

Several factors impact the needed DOI for a particular herd:

When vaccination occurs (dry off, close up, post-fresh, etc.)

When breeding begins

When animals become pregnant

Critical risk period for each pathogen

The following two scenarios represent the level of protection during the critical risk period for BVD and IBR, which is 281 days. One example illustrates adequate protection while the other demonstrates that the vaccine’s DOI is inadequate to protect the cow against these pathogens through the full gestation.

Adequate Protection

35 days in milk (DIM) at vaccination

Diagnosed pregnant at 80 DIM

Duration of immunity of vaccine (365 days) (DOI = 35+365 = 400 DIM)

DIM at calving (80+281 = 361)

Lacking Protection

35 DIM at vaccination

Diagnosed pregnant at 175 DIM

Duration of immunity of vaccine (365 days) (DOI = 35+365 = 400 DIM)

DIM at calving (175+281 = 456)

To stay ahead of disease issues that affect your reproductive program, select a vaccine with a proven DOI that helps provide protection through the critical risk periods for the most common pathogens. Remember that each herd is different. Talk to your herd veterinarian to discuss vaccine selection and vaccination program schedules that best fit your operation and management needs.